Iran and the P5+1 countries decided Friday to extend talks about the Iranian nuclear program for another four months, officials said.

Delegates from Iran and the P5+1 countries -- the five permanent members of the UN Security Council (Britain, China, France, Russia and the United States) plus Germany -- have been engaged in negotiations about Iran's program since November. At that time, Iran agreed to halt its enrichment of uranium to higher levels and allow access to international inspectors.

U.S. Secretary of State John Kerry said sanctions against oil sales and other sources of income would still be in place, though Iran would get $2.8 billion in assets that had been frozen in the United States.

"Let me be clear," he said in a statement, "Iran will not get any more money during these four months than it did during the last six months, and the vast majority of its frozen oil revenues will remain inaccessible."

In return, Iran agreed to dilute stocks of material or turn it into metal plates as reactor fuel, neither of which allow it to easily be used as bomb-grade fuel, the New York Times reported.

"Our negotiators have made progress in some areas and, while real gaps remain, there is a credible prospect for a comprehensive deal," a release from the White House press secretary said. "Because of this -- and because Iran has upheld its commitments under the initial accord -- we agreed today to extend the Joint Plan of Action to Nov. 24. This extension will allow us to continue the negotiations while ensuring that the progress of Iran's nuclear program remains halted during the negotiations."